1. Field of the Invention
The present invention relates to a method for determining with a high level of accuracy the therapeutic activity in mammals, including man, of a class of peptidomimetic compounds that are inhibitors of metalloproteinase enzymes present in snake venom.
The invention further relates to new compounds of the class indicated above, as well as their therapeutic use in a large number of important human diseases, including tumoral invasion, rheumatoid arthritis, periodontitis, corneal ulcers, multiple sclerosis, aneurism of the aorta, osteoporosis, the cicatrization of wounds, contact dermatitis, arteriosclerosis, septic shock, parasite invasion, hypertension, allergies, defective immune response, Alzheimer's disease, chronic bronco-pulmonitis, pulmonary emphysema, cirrhosis of the liver, dilatational cardiomyopathy and dysfunctions in the reproductive system.
2. Description of the Related Art
Snake venom may be many types of complex mixtures, containing a wide variety of proteolytic enzymes which digest prey or alter the physiological functions of prey, particularly physiological functions such as the circulatory system. In fact, it is well known that the venom from snakes belonging to the family of the Viperidae have profound effects on the hemostatic and fibrinolytic systems, showing procoagulant or, alternatively, anti-coagulant activities (see, for example, Critical Reviews in Toxicology, 21:171-182, 1991). In a similar manner, factors that have a powerful inhibiting effect on blood platelet aggregation have been found in snake venom, along with others that interfere with activation of prothrombin or fibrin.
An extremely important class of enzymes found in the venom of snakes belonging to the family Crotalidae are the so-called hemorrhagic factors, or hemorrhaging. These are structurally of use to the snake, as they rapidly induce extensive internal hemorrhages in the victims, causing circulatory collapse and preventing the victim from escaping its fate. The mechanism of the hemorrhagic action is due to the particular ease with which the enzymes are capable of degrading a large number of filiform proteins which bind between them the various vasal endothelial cells, allowing the elements of the blood to escape from the vessels. Recent studies have made it possible to ascertain that the hemorrhagic factors, comprising a large number of enzymes isolated from venom, have an extremely varied molecular weight (usually between 20 and 90 KDa), and often contain a number of functional sub-units delegated for hemorrhagic, blood platelet anti-aggregant and adhesive activities (see, for example, Pharmacology and Therapeutics, 62:325-372, 1994). Although their molecular weights differ greatly, the hemorrhagins have several fixed characteristics on the catalytic site, e.g., in the way that zinc bonds to certain amino acids in the protein chain, and the way in which they attack the proteins in the basal membrane of blood vessels.
The presence of zinc in the active site is not exclusive to hemorrhaging, but is characteristic of a wide number of proteolytic enzymes that perform important physiological and pathological functions in animals, from the smallest and most simple to the most highly evolved. Through the study of the sequences in residues from the protein chain and the amino acids involved in zinc bonding it has been possible to obtain a sort of "family tree" for this family of proteases (see, for example, FEBS Letters, 312:110-114, 1992). It has, thus, been seen that enzymes belonging to widely differing living beings, such as astatin (extracted from a river crustacean), serratin (obtained from a microorganism), matrixins (present in the organism of mammals, where they have important effects on cell migration and the reconstruction of damaged tissue) and the hemorrhagic factors of snake venom, in reality differ only in one of the four amino acids binding zinc in the active site, and can thus, in a certain sense, be considered as distantly related to each other. However, this does not mean that the functions performed by these enzymes are similar. It has, in fact, been clarified that the proteolytic enzymes of snake venom have no similarity, either structural or functional, with any other protein in the plant or animal world, with the exception of the zinc site. However, they are very similar to each other, and they all appear to derive from a single ancestral gene. This similarity makes it possible to define a new family of proteinases: the snake venom metalloproteinases (see, for example, Biol. Chem. Hopp-Seyler, 373:381-385, 1992).
Citation of any document herein is not intended as an admission that such document is pertinent prior art or is considered material to the patentability of any claim of the present application. Any statement as to content or a date of any document is based on the information available to applicants at the time of filing and does not constitute an admission as to the correctness of such a statement.